On Wed, 23 Jul 2003 09:17:16 -0700, "Simon Robertson"
<shroud_security@hotmail.com> wrote:

New Scientist just published the following article:
Big Bang afterglow reveals dark energy's repulsion

http://www.newscientist.com/news/news.jsp?id=ns99993963

in which, and I quote, "a team of astronomers analysed changes in the energy
of cosmic microwave background (CMB ) photons caused by the gravity of
massive concentrations of galaxies. As photons pass through these galactic
masses, gravitational potential causes them to gain and then lose energy.
Once the photon has passed through, the energy changes should have cancelled
out."
"But the CMB photons studied had slightly higher energy levels on leaving
the galaxy concentrations. This change can only be explained by invoking the
influence of dark energy in the expansion of these massive galactic
structures."

What I would like to know is how do scientist reconcile this apparent
spontaneous increase in energy of the photons with the third law of
thermodynamics (entropy)? Is entropy increasing here or decreasing?

Thanks

Simon

Interesting question. Another thing that I've been recently
considering is the negative pressure that this so-called dark energy
exerts. If this dark energy were based on some new extremely exotic
material, and we could model it as a gas, according to the ideal gas
law, negative pressure would correspond to negative absolute
tempatures. Rather bizarre...